Stroke and the female brain

Al Meslamani A. Assessment of Knowledge and attitude towards Stroke among the UAE population during the COVID-19 pandemic: A cross-sectional study

Background: Despite significant advancements in healthcare, the burden of stroke continues to rise in the developed world, especially during the COVID-19 pandemic. Association between COVID-19 infection and stroke is well established. Factors identified for the delay in presentation and management include a lack of awareness regarding stroke. We aimed to assess the general public knowledge and attitudes on stroke and stroke risk factors in the United Arab Emirates during the COVID-19 pandemic. Methods: A cross-sectional study was conducted between September 2021 and January 2022 among adults≥ 18 years old. Participants completed a self-administered questionnaire on sociodemographic characteristics and stroke knowledge and attitudes. Knowledge and attitude scores were calculated based on the number of correct responses. Linear regression analysis was performed to determine the factors related to knowledge and attitude towards stroke. Results: Of the 500 respondents, 69.4% were females, 53.4% were aged between 18 and 25, and nearly half were students (48.4%). The mean knowledge score was 13.66 (range 2-24). Hypertension (69%), smoking (63.2%), stress (56.4%) obesity/overweight (54.4%), and heart disease (53.6%) were identified as risk factors. Overall, the knowledge of signs/symptoms was suboptimal. The mean attitude score was 4.41 (range, 1-6); 70.2% would call an ambulance if someone were having a stroke. A monthly income of 11,000-50,000 AED and being a student were associated with positive knowledge. Being a non-health worker and lacking access to electronic media sources were associated with worse attitudes. Conclusion: Overall, we identified poor knowledge and suboptimal attitudes toward stroke. These findings reflect the need for effective public health approaches to improve stroke awareness, knowledge, and attitudes for effective prevention in the community. Presently, this is of utmost necessity, given the increased occurrence of stroke and its severity among COVID-19 patients.

Stroke in women between 2006 and 2018: Demographic, socioeconomic, and age disparities

BACKGROUND

Black Americans have a higher prevalence of stroke and stroke-related deaths than any other racial group. Racial disparities in stroke outcomes are even wider among women than men. Conventional studies have cited differences in lifestyle (i.e. smoking, alcohol consumption, etc.) and vascular risk factors between races as the source of these disparities. However, these studies fail to account for the higher prevalence of minoritized populations at the lower end of the socioeconomic distribution.

OBJECTIVES

This study explores differences in stroke risk factors across age and socioeconomic cohorts to determine whether comorbidities can sufficiently explain disparities at all ages and income levels.

DESIGN

Using the 2006-2018 National Health Interview Survey data, statistical analysis evaluated differences in risk factors among a full sample cohort (aged 18-85 years; n = 131,091) and a "young" subsample cohort (aged 18-59 years; n = 6183) of women.

METHODS

Logistics and unconditional quantile regression models assessed the relationship between stroke and comorbid, demographic, and behavioral characteristics across socioeconomic classes.

RESULTS

Results suggest that Black women had a 1.415-fold (confidence interval = 1.259, 1.591) higher likelihood of stroke compared with White women after controlling for age, behavior, and comorbidities. Racial disparities were not statistically significant at the higher income ranges for either the full (odds ratio = 1.404, p = 0.3114) or young samples (odds ratio = 1.576, p = 0.7718). However, Blacks had significantly higher odds of stroke in the lower quartiles (lower odds ratio: 1.329, p = 0.0242; lower middle odds ratio: 1.233, p = 0.0486; and upper middle odds ratio: 1.994, p = 0.0005). Disparities were larger among young women (odds ratio = 1.449, confidence interval = 1.211, 1.734).

CONCLUSION

While comorbidities were highly associated with stroke prevalence in all socioeconomic cohorts, Blacks only had higher relative odds in the lower income classes. Lack of biological or behavioral explanations for these findings suggests that unobserved or uncontrolled factors such as systemic racism, prejudicial institutions, or differential treatment may contribute to this.

Sexual dimorphism in immune cell responses following stroke

Recent bodies of work in regard to stroke have revealed significant sex differences in terms of risk and outcome. While differences in sex hormones have been the focus of earlier research, the reasons for these differences are much more complex and require further identification. This review covers differences in sex related immune responses with a focus on differences in immune cell composition and function. While females are more susceptible to immune related diseases, they seem to have better outcomes from stroke at the experimental level with reduced pro-inflammatory responses. However, at the clinical level, the picture is much more complex with worse neurological outcomes from stroke. While the use of exogenous sex steroids can replicate some of these findings, it is apparent that many other factors are involved in the modulation of immune responses. As a result, more research is needed to better understand these differences and identify appropriate interventions and risk modification.

Influenza Vaccination and Risk of Stroke in Women With Chronic Obstructive Pulmonary Disease: A Nationwide, Population-Based, Propensity-Matched Cohort Study

Backgrounds

The risk of stroke is higher among patients with chronic obstructive pulmonary disease (COPD) than among the healthy population. Moreover, women generally have worse long-term stroke outcomes than men.

Methods

The data of 6681 women with COPD (aged ≥ 65 years) registered in Taiwan’s National Health Insurance Research Database were retrospectively analyzed from January 1, 2001 to December 31, 2011. After 1:1 propensity score matching, the patients were divided into vaccinated and unvaccinated groups.

Results

In total, 5102 women were enrolled. The vaccinated group had a significantly lower risk of total, hemorrhagic, and ischemic stroke than the unvaccinated group (adjusted hazard ratio [aHR]: 0.60, 95% confidence interval [CI]: 0.54–0.67; aHR: 0.59, 95% CI: 0.43–0.83; and aHR: 0.59, 95% CI: 0.52–0.68, respectively). A lower risk of stroke was observed among the women aged 65–74 and ≥75 years, and the association was dose-dependent in all types of stroke (aHR: 1.08, 95% CI: 0.92–1.26; aHR: 0.70, 95% CI: 0.60–0.82; and aHR: 0.32, 95% CI: 0.26–0.38 for those vaccinated 1, 2 to 3, and ≥4 times, respectively, during the follow-up period). Women with a CHA2DS2-VASc score (conditions and characteristics included congestive heart failure, hypertension, diabetes, stroke, vascular disease, age, and sex) of 2–3 and ≥4 had a significantly lower risk of ischemic stroke while receiving more vaccinations. A smaller significant lower risk of hemorrhagic stroke after more than 4 times of vaccination was noted in the women with a CHA2DS2-VASc score of ≥4. Both interrupted and non-interrupted vaccination was associated with lower risk of stroke occurrence.

Conclusion

Influenza vaccination is associated with a lower risk of total, hemorrhagic, and ischemic stroke among women with COPD, and the association is dose-dependent. However, the findings may be limited by unmeasurable confounders. Further investigations on this subject are warranted.

Potential nanotherapeutic strategies for perioperative stroke

AIMS

Based on the complex pathological environment of perioperative stroke, the development of targeted therapeutic strategies is important to control the development of perioperative stroke.

DISCUSSIONS

Recently, great progress has been made in nanotechnology, and nanodrug delivery systems have been developed for the treatment of ischemic stroke.

CONCLUSION

In this review, the pathological processes and mechanisms of ischemic stroke during perioperative stroke onset were systematically sorted. As a potential treatment strategy for perioperative stroke, the review also summarizes the multifunctional nanodelivery systems based on ischemic stroke, thus providing insight into the nanotherapeutic strategies for perioperative stroke.

Sex Differences in the Risk of 30-Day Death After Acute Ischemic Stroke

Objective

To examine sex differences in early stroke deaths according to cause of death.

Methods

We investigated 30-day deaths in patients with acute ischemic stroke enrolled in a multicenter stroke registry between 2007 and 2019 in Fukuoka, Japan. We estimated the multivariable-adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) of cause-specific deaths for women vs men using Cox proportional hazards models and competing risk models. The risk of acute infections during hospitalization and the associated case fatality rates were also compared between the sexes.

Results

Among 17,956 patients with acute ischemic stroke (women: 41.3%), the crude 30-day death rate after stroke was higher in women than men. However, adjusting for age and stroke severity resulted in a lower risk of death among women (HR [95% CI]: 0.76 [0.62-0.92]). Analyses using competing risk models revealed that women were less likely to die of acute infections (subdistribution HR [95% CI]: 0.33 [0.20-0.54]). Further analyses showed that women were associated with a lower risk of acute infections during hospitalization (OR [95% CI]: 0.62 [0.52-0.74]) and a lower risk of death due to these infections (subdistribution HR [95% CI]: 052 [0.33-0.83]).

Conclusions

When adjusting for confounders, the female sex was associated with a lower risk of 30-day death after stroke, which could be explained by a female survival advantage in poststroke infections. Sex-specific strategies are needed to reduce early stroke deaths.

Classification of Evidence

This is a Class I prognostic study because it is a prospective population-based cohort with objective outcomes. Female sex appears to be protective against early stroke deaths and post stroke infections.

Covid-19 Kills More Men Than Women: An Overview of Possible Reasons

The high mortality observed in Covid-19 patients may be related to unrecognized pulmonary embolism, pulmonary thrombosis, or other underlying cardiovascular diseases. Recent data have highlighted that the mortality rate of Covid-19 seems to be higher in male patients compared to females. In this paper, we have analyzed possible factors that may underline this sex difference in terms of activity of the immune system and its modulation by sex hormones, coagulation pattern, and preexisting cardiovascular diseases as well as effects deriving from smoking and drinking habits. Future studies are needed to evaluate the effects of sex differences on the prevalence of infections, including Covid-19, its outcome, and the responses to antiviral treatments.

lncRNA ANRIL Ameliorates Oxygen and Glucose Deprivation (OGD) Induced Injury in Neuron Cells via miR-199a-5p/CAV-1 Axis

Ischemia stroke is one of the leading causes of death and disability in the world. Long non-coding RNA ANRIL has been reported to play an important role in ischemic injury. In this study, we aim to explore the mechanism by which ANRIL exhibits protective effect. Middle cerebral artery occlusion mouse models were applied and infarction areas were assessed by TTC assay. The expression of ANRIL and miR-199a-5p were determined by qPCR. Oxygen and glucose deprivation treatment was applied to mimic in vitro ischemia injury in N-2a cells. The levels of BCL-2, BAX, MEK, ERK, CAV-1 were determined by western blot. Cell viability were assessed by MTT assay. The direct interaction among miR-199a-5p and ANRIL, miR-199a-5p and CAV-1 were demonstrated by dual Luciferase report assay. ANRIL and miR-199a-5p expression were changed in both in vivo and in vitro ischemia model. Overexpression of ANRIL or inhibition of miR-199a-5p could protect cells against ischemia induced injury by elevating cell viability through CAV-1 mediated MEK/ERK pathway. miR-199a-5p attenuated CAV-1 expression by direct targeting. ANRIL competitively interacted with miR-199a-5p in N-2a cells, leading to a de-repression of CAV-1. ANRIL protects N-2a cells against ischemia induced injury by elevated CAV-1 by competitively interacting with miR-199a-5p, thus activating MEK/ERK pathway and elevating cell viability.

Stress, sex hormones, inflammation, and major depressive disorder: Extending Social Signal Transduction Theory of Depression to account for sex differences in mood disorders

Social Signal Transduction Theory of Depression is a biologically plausible, multi-level theory that describes neural, physiologic, molecular, and genomic mechanisms that link experiences of social-environmental adversity with internal biological processes that drive depression pathogenesis, maintenance, and recurrence. Central to this theory is the hypothesis that interpersonal stressors involving social threat (e.g., social conflict, evaluation, rejection, isolation, and exclusion) upregulate inflammatory processes that can induce several depressive symptoms, including sad mood, anhedonia, fatigue, psychomotor retardation, and social-behavioral withdrawal. The original article describing this formulation (Psychol Bull 140:774-815, 2014) addressed critical questions involving depression onset and recurrence, as well as why depression is strongly predicted by early life stress and comorbid with anxiety disorders and certain physical disease conditions, such as asthma, rheumatoid arthritis, chronic pain, and cardiovascular disease. Here, we extend the theory to help explain sex differences in depression prevalence, which is a defining feature of this disorder. Central to this extension is research demonstrating that ovarian hormone fluctuations modulate women's susceptibility to stress, brain structure and function, and inflammatory activity and reactivity. These effects are evident at multiple levels and are highly context-dependent, varying as a function of several factors including sex, age, reproductive state, endogenous versus exogenous hormones, and hormone administration mode and dose. Together, these effects help explain why women are at greater risk for developing inflammation-related depressed mood and other neuropsychiatric, neurodevelopmental, and neurodegenerative disorders during the reproductive years, especially for those already at heightened risk for depression or in the midst of a hormonal transition period.

Oophorectomy Reduces Estradiol Levels and Long-Term Spontaneous Neurovascular Recovery in a Female Rat Model of Focal Ischemic Stroke

Although epidemiological evidence suggests significant sex and gender-based differences in stroke risk and recovery, females have been widely under-represented in preclinical stroke research. The neurovascular sequelae of brain ischemia in females, in particular, are largely uncertain. We set out to address this gap by a multimodal in vivo study of neurovascular recovery from endothelin-1 model of cortical focal-stroke in sham vs. ovariectomized female rats. Three weeks post ischemic insult, sham operated females recapitulated the phenotype previously reported in male rats in this model, of normalized resting perfusion but sustained peri-lesional cerebrovascular hyperreactivity. In contrast, ovariectomized (Ovx) females showed reduced peri-lesional resting blood flow, and elevated cerebrovascular responsivity to hypercapnia in the peri-lesional and contra-lateral cortices. Electrophysiological recordings showed an attenuation of theta to low-gamma phase-amplitude coupling in the peri-lesional tissue of Ovx animals, despite relative preservation of neuronal power. Further, this chronic stage neuronal network dysfunction was inversely correlated with serum estradiol concentration. Our pioneering data demonstrate dramatic differences in spontaneous recovery in the neurovascular unit between Ovx and Sham females in the chronic stage of stroke, underscoring the importance of considering hormonal-dependent aspects of the ischemic sequelae in the development of novel therapeutic approaches and patient recruitment in clinical trials.

Age- and sex-related difference of lipid profile in patients with ischemic stroke in China

Age- and sex-related differences of lipid profiles were not well understood among ischemic stroke patients in China. Our study aimed to investigate the relationship between lipid abnormalities and ischemic stroke in China. A retrospective analysis was performed involving 2074 patients with ischemic stroke who admitted to Meizhou People's Hospital (Huangtang Hospital), Meizhou Hospital Affiliated to Sun Yat-sen University between January 1, 2014 and March 1, 2017. Our study indicated that there were significant differences in total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), non-high density lipoprotein cholesterol (non-HDL), and Apolipoprotein A (ApoA) between male and female patients. Meanwhile, different lipid levels including TC, TG, and ApoA were observed for patients of various age groups. The nonelderly patients tended to have higher lipid levels than elderly patients. Isolated low HDL (namely, normal LDL + low HDL + normal TG) was the most common lipid abnormalities in patients. In conclusion, there was age- and sex-related difference in lipid profiles among patients with ischemic stroke. Age, sex as well as some other factors should be carefully considered for lipid management in patients with ischemic stroke in China.

Neuroprotective Effects of Guanosine Administration on In Vivo Cortical Focal Ischemia in Female and Male Wistar Rats

Guanosine (GUO) has neuroprotective effects in experimental models of brain diseases involving glutamatergic excitotoxicity in male animals; however, its effects in female animals are poorly understood. Thus, we investigated the influence of gender and GUO treatment in adult male and female Wistar rats submitted to focal permanent cerebral ischemia in the motor cortex brain. Female rats were subdivided into non-estrogenic and estrogenic phase groups by estrous cycle verification. Immediately after surgeries, the ischemic animals were treated with GUO or a saline solution. Open field and elevated plus maze tasks were conducted with ischemic and naïve animals. Cylinder task, immunohistochemistry and infarct volume analyses were conducted only with ischemic animals. Female GUO groups achieved a full recovery of the forelimb symmetry at 28-35 days after the insult, while male GUO groups only partially recovered at 42 days, in the final evaluation. The ischemic insult affected long-term memory habituation to novelty only in female groups. Anxiety-like behavior, astrocyte morphology and infarct volume were not affected. Regardless the estrous cycle, the ischemic injury affected differently female and male animals. Thus, this study points that GUO is a potential neuroprotective compound in experimental stroke and that more studies, considering the estrous cycle, with both genders are recommended in future investigation concerning brain diseases.

Interaction of Sex and Diabetes on Outcome After Ischemic Stroke

Background

The relationship between ischemic stroke (IS), diabetes mellitus (DM), and sex is intriguing. The aim of this study was to assess the effect modification of sex in the association between DM and short- and long-term disability and mortality in first-ever IS patients.

Methods

In a retrospective, observational, hospital-based study of a prospective series including first-ever IS patients from January 2006 until July 2011, differences in 3-month and 5-year mortality, and disability between diabetic and non-diabetic patients [modified Rankin Scale (mRS) from 3 to 5] were analyzed by sex.

Results

In total, 933 patients (36.3% with DM, 50.5% women) were included. Overall 3-month and 5-year mortality were 150 (16.1%) and 407 (44.1%), respectively. Adjusted for age, previous mRS, and stroke severity, patients with DM had significantly higher 3-month disability [hazard ratio (HR): 1.49 (95% confidence interval (CI): 1.39–1.70), p < 0.0001], 5-year disability [HR: 1.41 (95% CI: 1.07–1.86), p = 0.015], and 5-year mortality [HR: 1.48 (95% CI: 1.20–1.81), p < 0.0001], compared with the non-DM group. Compared with non-DM women, women with diabetes had worse 3-month disability [HR: 1.81 (95% CI: 1.33–2.46), p < 0.0001] and 5-year mortality [HR: 1.72 (95% CI: 1.30–2.20), p < 0.0001], and a trend for 5-year disability [HR: 1.40 (95% CI: 0.99–2.09), p = 0.057]. In men, DM had an effect on 3-month disability [HR: 1.45 (95% CI: 1.07–1.96), p = 0.018], a trend for 5-year disability [HR: 1.43 (95% CI: 0.94–2.19), p = 0.096], but no clear effect on 5-year mortality [HR: 1.22 (95% CI: 0.91–1.65), p = 0.186].

Conclusion

Sex has a modifier effect on mortality in first-ever IS diabetic patients. Long-term mortality is increased in diabetic women compared with non-diabetic women, a difference not observed in men.

Cerebrovascular Hemodynamics in Women

Sex and gender, as biological and social factors, significantly influence health outcomes. Among the biological factors, sex differences in vascular physiology may be one specific mechanism contributing to the observed differences in clinical presentation, response to treatment, and clinical outcomes in several vascular disorders. This review focuses on the cerebrovascular bed and summarizes the existing literature on sex differences in cerebrovascular hemodynamics to highlight the knowledge deficit that exists in this domain. The available evidence is used to generate mechanistically plausible and testable hypotheses to underscore the unmet need in understanding sex-specific mechanisms as targets for more effective therapeutic and preventive strategies.

Association of miR-146a, miR-149, miR-196a2, miR-499 gene polymorphisms with ischemic stroke in a Chinese people

This study aimed to investigate genetic polymorphisms of miR-146a, miR-149, miR-196a2, and miR-499 and genetic susceptibility of ischemic stroke in the population of Guangxi in China. A case–control study was used to investigate miRNAs genetic polymorphisms in 298 patients with ischemic stroke and 303 healthy controls. Single-base extension polymerase chain reaction genotyping principle was used to detect genetic polymorphisms of miRNAs,and the relationship of genotype in each group and blood lipid was compared and analyzed. The genetic polymorphism of miR-499A>G (rs3746444) was associated with ischemic stroke (P < 0.05), and the risk of ischemic stroke was high in patients with G allele (OR = 1.455; 95% CI = 0.531–2.381; P = 0.039) and AG (OR = 1.339; 95% CI = 1.126–1.967; P = 0.037) genotype. The levels of low-density lipoprotein cholesterol, very-low-density lipoprotein cholesterol, homocysteine, and lipoprotein in the ischemic stroke group were higher than those in the control group (P < 0.05). The genetic polymorphism of miR-499A>G (rs3746444) was related to ischemic stroke, and G allele and AG genotype may increase the risk of ischemic stroke in the population of Guangxi in China.

NOSH-NBP, a Novel Nitric Oxide and Hydrogen Sulfide- Releasing Hybrid, Attenuates Ischemic Stroke-Induced Neuroinflammatory Injury by Modulating Microglia Polarization

NOSH-NBP, a novel nitric oxide (NO) and hydrogen sulfide (H2S)-releasing hybrid, protects brain from ischemic stroke. This study mainly aimed to investigate the therapeutic effect of NOSH-NBP on ischemic stroke and the underlying mechanisms. In vivo, transient middle cerebral artery occlusion (tMCAO) was performed in C57BL/6 mice, with NO-NBP and H2S-NBP as controls. NO and H2S scavengers, carboxy-PTIO and BSS, respectively, were used to quench NO and H2S of NOSH-NBP. In vitro, BV2 microglia/BMDM were induced to the M1/2 phenotype, and conditioned medium (CM) experiments in BV2 microglia, neurons and b.End3 cerebral microvascular endothelial cells (ECs) were performed. Microglial/macrophage activation/polarization was assessed by flow cytometry, Western blot, RT-qPCR, and ELISA. Neuronal and EC survival was measured by TUNEL, flow cytometry, MTT and LDH assays. Transmission electron microscopy, EB extravasation, brain water content, TEER measurement and Western blot were used to detect blood-brain barrier (BBB) integrity and function. Interestingly, NOSH-NBP significantly reduced cerebral infarct volume and ameliorated neurological deficit, with superior effects compared with NO-NBP and/or H2S-NBP in mice after tMCAO. Both NO and H2S-releasing groups contributed to protection by NOSH-NBP. Additionally, NOSH-NBP decreased neuronal death and attenuated BBB dysfunction in tMCAO-treated mice. Furthermore, NOSH-NBP promoted microglia/macrophage switch from an inflammatory M1 phenotype to the protective M2 phenotype in vivo and in vitro. Moreover, the TLR4/MyD88/NF-κB pathway and NLRP3 inflammasome were involved in the inhibitory effects of NOSH-NBP on M1 polarization, while peroxisome proliferator activated receptor gamma signaling contributed to NOSH-NBP induced M2 polarization. These findings indicated that NOSH-NBP is a potential therapeutic agent that preferentially promotes microglial/macrophage M1-M2 switch in ischemic stroke.

[Sex differences in acute disturbances of cerebral blood circulation]

It is shown that in the development of stroke observed sex differences, which manifest themselves both clinically and by laboratory parameters. While men have a higher incidence of stroke for most of his life, a woman in a more advanced age have a higher risk for stroke. Sex differences in the development of stroke depend on several factors, including genetic and hormonal changes throughout life. Studies sex differences in the risk of stroke is only in the initial stage, but the first results show that there are differences in neuronal cell death in males and females after experimental ischemic stroke. A better understanding of the mechanisms underlying the development of stroke in men and women will lead to more appropriate treatment strategies for patients of both sexes.

Effects of a Dietary Beetroot Juice Treatment on Systemic and Cerebral Haemodynamics- A Pilot Study

INTRODUCTION

Beetroot Juice (BJ) contains dietary nitrates that increase the blood Nitric Oxide (NO) level, decrease Blood Pressure (BP), increase athletic performance and improve cognitive functions but the mechanism remains unclear. Ultrasonographic measurement of middle cerebral artery blood flow velocity with computation of Cerebral Augmentation Index (CAIx) is a measure of the reflected flow signal, modulated by changes in cerebrovascular resistance and compliance.

AIM

This pilot study tests the hypothesis that ingestion of an amount of BJ sufficient to raise the blood NO level two-to three-fold, decreases Transcranial Doppler (TCD) measured CAIx.

MATERIALS AND METHODS

Ten healthy young-adult African-American women were studied at two levels of submaximal exercise, 40% and 80% of their predetermined peak oxygen consumptions. The subjects ingested nitrate-free orange juice (OJ, control) and an isocaloric BJ beverage (1.5 mg/mL nitrate, 220 Cal), on different days, 1-2 weeks apart.

RESULTS

The BJ treatment increased blood NO and decreased systolic BP at rest and at the two levels of exercise. The BJ treatment decreased CAIx only at the two levels of exercise (from 79 ± 2% to 62 ± 2% and from 80 ± 2% to 60 ± 3%, p<0.05). Exercise increased TCD-measured resistance and pulsatility indices (RIx, PIx) without changing AIx. The BJ treatment had no effect on RIx and PIx.

CONCLUSION

These findings suggest that decreased CAIx associated with aerobic exercise reflects the change in cerebral haemodynamics resulting from dietary nitrate supplementation. Future studies should determine whether the BJ-induced decrement in CAIx is correlated with an improvement in brain function.

Alterations in the corticotropin-releasing hormone (CRH) neurocircuitry: Insights into post stroke functional impairments

Although it is well accepted that changes in the regulation of the hypothalamic-pituitary adrenal (HPA) axis may increase susceptibility to affective disorders in the general population, this link has been less examined in stroke patients. Yet, the bidirectional association between depression and cardiovascular disease is strong, and stress increases vulnerability to stroke. Corticotropin-releasing hormone (CRH) is the central stress hormone of the HPA axis pathway and acts by binding to CRH receptors (CRHR) 1 and 2, which are located in several stress-related brain regions. Evidence from clinical and animal studies suggests a role for CRH in the neurobiological basis of depression and ischemic brain injury. Given its importance in the regulation of the neuroendocrine, autonomic, and behavioral correlates of adaptation and maladaptation to stress, CRH is likely associated in the pathophysiology of post stroke emotional impairments. The goals of this review article are to examine the clinical and experimental data describing (1) that CRH regulates the molecular signaling brain circuit underlying anxiety- and depression-like behaviors, (2) the influence of CRH and other stress markers in the pathophysiology of post stroke emotional and cognitive impairments, and (3) context and site specific interactions of CRH and BDNF as a basis for the development of novel therapeutic targets. This review addresses how the production and release of the neuropeptide CRH within the various regions of the mesocorticolimbic system influences emotional and cognitive behaviors with a look into its role in psychiatric disorders post stroke.

Field Synopsis of the Role of Sex in Stroke Prediction Models

Background

Guidelines for stroke prevention recommend development of sex‐specific stroke risk scores. Incorporating sex in Clinical Prediction Models (CPMs) may support sex‐specific clinical decision making. To better understand their potential to guide sex‐specific care, we conducted a field synopsis of the role of sex in stroke‐related CPMs.

Methods and Results

We identified stroke‐related CPMs in the Tufts Predictive Analytics and Comparative Effectiveness CPM Database, a systematic summary of cardiovascular CPMs published from January 1990 to May 2012. We report the proportion of models including the effect of sex on stroke incidence or prognosis, summarize the directionality of the predictive effects of sex, and explore factors influencing the inclusion of sex. Of 92 stroke‐related CPMs, 30 (33%) contained a coefficient for sex or presented sex‐stratified models. Only 12/58 (21%) CPMs predicting outcomes in patients included sex, compared to 18/30 (60%) models predicting first stroke (P<0.0001). Sex was most commonly included in models predicting stroke among a general population (69%). Female sex was consistently associated with reduced mortality after ischemic stroke (n=4) and higher risk of stroke from arrhythmias or coronary revascularization (n=5). Models predicting first stroke versus outcomes among patients with stroke (odds ratio=5.75, 95% CI 2.18–15.14, P<0.001) and those developed from larger versus smaller sample sizes (odds ratio=4.58, 95% CI 1.73–12.13, P=0.002) were significantly more likely to include sex.

Conclusions

Sex is included in a minority of published CPMs, but more frequently in models predicting incidence of first stroke. The importance of sex‐specific care may be especially well established for primary prevention.

Field Synopsis of Sex in Clinical Prediction Models for Cardiovascular Disease

BACKGROUND

Several widely used risk scores for cardiovascular disease (CVD) incorporate sex effects, yet there has been no systematic summary of the role of sex in clinical prediction models (CPMs). To better understand the potential of these models to support sex-specific care, we conducted a field synopsis of sex effects in CPMs for CVD.

METHODS AND RESULTS

We identified CPMs in the Tufts Predictive Analytics and Comparative Effectiveness CPM Registry, a comprehensive database of CVD CPMs published from January 1990 to May 2012. We report the proportion of models including sex effects on CVD incidence or prognosis, summarize the directionality of the predictive effects of sex, and explore factors influencing the inclusion of sex. Of 592 CVD-related CPMs, 193 (33%) included sex as a predictor or presented sex-stratified models. Sex effects were included in 78% (53/68) of models predicting incidence of CVD in a general population, versus only 35% (59/171), 21% (12/58), and 17% (12/72) of models predicting outcomes in patients with coronary artery disease, stroke, and heart failure, respectively. Among sex-including CPMs, women with heart failure were at lower mortality risk in 8 of 8 models; women undergoing revascularization for coronary artery disease were at higher mortality risk in 10 of 12 models. Factors associated with the inclusion of sex effects included the number of outcome events and using cohorts at-risk for CVD (rather than with established CVD).

CONCLUSIONS

Although CPMs hold promise for supporting sex-specific decision making in CVD clinical care, sex effects are included in only one third of published CPMs.

The impact of gender on stroke pathology and treatment

Cerebral ischemic stroke is a leading cause of mortality and functional disability. However, unfortunately few effective treatments exist to counteract the deleterious pathological mechanisms triggered following an ischemic event. Epidemiological and experimental studies have revealed a significant difference in the vulnerability of males versus females to both the incidence of stroke and amount of resulting pathology following an ischemic stroke which is also dependent on the stage of lifespan. Here we review the evidence for gender differences in both the overall pathology and cellular mechanisms of injury following ischemic stroke. In addition, we discuss the evidence for any gender differences that may occur in the effectiveness of treatments and how this supports the need for the investigation and development of gender-specific therapies.

Strategies for improving cardiovascular health in women with diabetes mellitus: a review of the evidence

Knowledge about cardiovascular (CV) disease in women with diabetes mellitus (DM) has changed substantially over the past 20 years. Coronary artery disease, strokes, and peripheral vascular disease affect women with DM at higher rates than the general population of women. Lifestyle therapies, such as dietary changes, physical activity, and smoking cessation, offer substantial benefits to women with DM. Of the pharmacotherapies, statins offer the most significant benefits but may not be well tolerated in some women. Aspirin may also benefit high-risk women. Other pharmacotherapies, such as fibrates, ezetimibe, niacin, fish oil, and hormone replacement therapy, remain unproven and, in some cases, potentially dangerous to women with DM. To reduce CV events, risks to women with DM must be better publicized and additional research must be done. Finally, advancements in health care delivery must target high-risk women with DM to lower risk factors and effectively improve cardiovascular health.

Gender Differences in Risk Factor and Clinical Outcome in Patients with Ischemic Stroke

Objective: Gender is an important determinant for risk factors and outcomes of ischemic stroke. The aim of this study was to compare risk factors, and clinical outcomes after ischemic stroke between male and female patients. Methods: The hospital records of patients with ischemic stroke were reviewed retrospectively. Demographic data, stroke risk factors, clinical severities and outcomes after stroke were collected and compared between male and female patients. Stroke severity and clinical disability after ischemic stroke were evaluated by means of the National Institutes of Health Stroke Scale (NIHSS) and modified Rankin Scale (mRS) respectively. Results: Among 447 patients with ischemic stroke, 195 (43.6%) patients were women. The mean age at ischemic stroke was higher in women than in men (p&lt;0.01). As compared to men, women had a significantly lower prevalence of hyperhomocysteinemia, smoking and drinking (all p&lt;0.01). NIHSS and mRS scores were not different between the 2 genders. Conclusions: Profiles of risk factors differed between the 2 genders, with men having a higher prevalence of hyperhomocysteinemia, smoking and drinking. There were no gender differences in stroke severity and disability after ischemic stroke.

Effect of sex and age interactions on functional outcome after stroke

Stroke is one of the leading causes of death and disability worldwide. Experimental and clinical studies showed that sex and age play an important role in deciding the outcome after stroke. At younger ages, males were shown to have a higher risk for stroke than females. However, this trend reverses in older ages particularly when females reach menopause. Many preclinical studies indicate that steroid hormones modulate the age-dependent differential stroke outcome. In addition, patterns of cell death pathways activated following cerebral ischemia are distinct between males and females, but independent of steroid hormones. Recent studies also indicate that microRNAs play important roles in mediating sex-specific stroke outcome by regulating stroke-related genes. This review discusses the contribution of sex and age to outcome after stroke with particular emphasis on the experimental studies that examined the effects of steroid hormones, differential cell death pathways, and involvement of sex-specific microRNAs following cerebral ischemia. Current understanding of the role of thrombolytic agents in stroke therapy is also discussed.

Circadian Variation of Stroke Onset: A Hospital-Based Study

Aims and background.

The circadian pattern of stroke occurrence variation has been recognized with certain differences between authors and stroke types. The underlying reason may be related to exogenous factors (cyclic physical activity, including sleep–awake cycles and assuming the up-right posture) and endogenous factors, with their diurnal variation (blood pressure, hemostatic balance, autonomic system activity). The aims of the present study are to investigate the existence of a circadian variation of stroke and the possible differences between stroke subtypes in the Cluj Napoca area.

Materials and method.

The stroke event data were acquired from the Patient Records of a consecutive series of 1083 patients admitted through the Emergency Room at Neurology Departments I and II of the District Hospital of Cluj Napoca, between 1 January 2012 and 31 December 2012. The classifiable onset time was assigned to one of four six-hour intervals: 00.01–06.00 (night), 06.01–12.00 (morning), 12.01–18.00 (afternoon) and 18.01–24.00 (evening). Demographic data and vascular risk factors were recorded.

Results.

All three stroke types (ischemic stroke, hemorrhagic stroke and subarachnoid hemorrhage) have shown a circadian variation regarding their occurrence, with the peak of incidence in the morning and the nadir during nighttime. This circadian pattern is independent by demographic factors and vascular risk factors.

Conclusion.

Our study confirmed the circadian variation of onset occurrence for all stroke subtypes. Some triggering factors promote ischemic stroke and prevent hemorrhagic stroke. The diurnal pattern of variation with the higher incidence in the morning and the lower in the night may lead to chrono-therapeutic and preventive approach (chrono-therapy of the risk factors), which targets the period of the highest vulnerability after awaking.

Sex differences in microRNA expression during development in rat cortex

There are important sex differences in the risk and outcome of conditions and diseases between males and females. For example, stroke occurs with greater frequency in men than in women across diverse ethnic backgrounds and nationalities. Work from our lab and others have revealed a sex-specific sensitivity to cerebral ischemia whereby males exhibit a larger extent of brain damage following an ischemic event compared to females. Studies suggest that the difference in male and female susceptibility to ischemia may be triggered by innate variations in gene regulation and protein expression between the sexes that are independent of post-natal exposure to sex hormones. We have shown that there are differences in microRNA (miRNA) expression in adult male and female brain following focal cerebral ischemia in mouse cortex. Herein we examine a role for differential expression of miRNAs during development in male and female rat cortex as potential effectors of the phenotype that leads to sex differences to ischemia. Expression studies in male and female cortices isolated from postnatal day 0 (P0), postnatal day 7 (P7), and adult rats using TaqMan Low Density miRNA arrays and NanoString nCounter analysis revealed differential miRNA levels between males and females at each developmental stage. We focused on the miR-200 family of miRNAs that showed higher levels in females at P0, but higher levels in males at P7 that persisted into adulthood, and validated the expression of miR-200a, miR-200b, and miR-429 by individual qRT-PCR as these are clustered on chromosome 5 and may be transcriptionally co-regulated. Prediction analysis of the miR-200 miRNAs revealed that genes within the Gonadotropin releasing hormone receptor pathway are the most heavily targeted. These studies support that developmental changes in miRNA expression may influence phenotypes in adult brain that underlie sexually dimorphic responses to disease, including ischemia.

Modifiable etiological factors and the burden of stroke from the Rotterdam study: a population-based cohort study

BACKGROUND

Stroke prevention requires effective treatment of its causes. Many etiological factors for stroke have been identified, but the potential gain of effective intervention on these factors in terms of numbers of actually prevented strokes remains unclear because of the lack of data from cohort studies. We assessed the impact of currently known potentially modifiable etiological factors on the occurrence of stroke.

METHODS AND FINDINGS

This population-based cohort study was based on 6,844 participants of the Rotterdam Study who were aged ≥55 y and free from stroke at baseline (1990-1993). We computed population attributable risks (PARs) for individual risk factors and for risk factors in combination to estimate the proportion of strokes that could theoretically be prevented by the elimination of etiological factors from the population. The mean age at baseline was 69.4 y (standard deviation 6.3 y). During follow-up (mean follow-up 12.9 y, standard deviation 6.3 y), 1,020 strokes occurred. The age- and sex-adjusted combined PAR of prehypertension/hypertension, smoking, diabetes mellitus, atrial fibrillation, coronary disease, and overweight/obesity was 0.51 (95% CI 0.41-0.62) for any stroke; hypertension and smoking were the most important etiological factors. C-reactive protein, fruit and vegetable consumption, and carotid intima-media thickness in combination raised the total PAR by 0.06. The PAR was 0.55 (95% CI 0.41-0.68) for ischemic stroke and 0.70 (95% CI 0.45-0.87) for hemorrhagic stroke. The main limitations of our study are that our study population comprises almost exclusively Caucasians who live in a middle and high income area, and that risk factor awareness is higher in a study cohort than in the general population.

CONCLUSIONS

About half of all strokes are attributable to established causal and modifiable factors. This finding encourages not only intervention on established etiological factors, but also further study of less well established factors. Please see later in the article for the Editors' Summary.

Seizures in the acute stroke setting

Stroke is one of the leading causes of long-term disability. One in six people in the world will suffer a stroke in their lifetime, with the annual incidence about 117 per 100,000 person-years in developing countries. It has also been shown to be the cause of 10-15% of epilepsies, more prevalent in patients above 60 years of age. The incidence of early seizures in acute stroke ranges 3-33%, with 50-78% of the seizures occurring within the first 24 hours. Occurrence of seizures within 24 hours of stroke is associated with higher 30-day mortality, which may be a reflection of severe neuronal damage. Alteration in intracellular ion concentrations and hyper-excitability are thought to be etiologies for early seizures in acute stroke, and the increased stress on already vulnerable tissues may result in worsening of stroke symptoms. Early detection of seizures and subsequent effective treatment can prevent additional metabolic burden and damage to the blood-brain barrier, which may improve recovery and overall outcome. Clinical seizures can be recognized readily at bedside and lead to prompt medical intervention. In contrast, electrographic seizures with subtle or no clinical sign and non-convulsive status epilepticus (NCSE) may escape clinical observation and be left untreated. With the use of continuous electroencephalogram monitoring (cEEG), patients with electrographic seizures can be better identified and medically treated more quickly. In addition to electrographic seizures, the presence of isolated and periodic epileptiform patterns on electroencephalogram (EEG) suggests the need for medical treatment since up to 75% of these patients have been found to develop early post-stroke seizures. Newer anti-epileptic medications with intravenous formulation, together with traditional regimen and barbiturate, have shown promise in controlling early post-stroke seizures and possibly improving outcome.

MicroRNA responses to focal cerebral ischemia in male and female mouse brain

Stroke occurs with greater frequency in men than in women across diverse ethnic backgrounds and nationalities. Work from our lab and others have revealed a sex-specific sensitivity to cerebral ischemia whereby males exhibit a larger extent of brain damage resulting from an ischemic event compared to females. Previous studies revealed that microRNA (miRNA) expression is regulated by cerebral ischemia in males; however, no studies to date have examined the effect of ischemia on miRNA responses in females. Thus, we examined miRNA responses in male and female brain in response to cerebral ischemia using miRNA arrays. These studies revealed that in male and female brains, ischemia leads to both a universal miRNA response as well as a sexually distinct response to challenge. Target prediction analysis of the miRNAs increased in male or female ischemic brain reveal sex-specific differences in gene targets and protein pathways. These data support that the mechanisms underlying sexually dimorphic responses to cerebral ischemia includes distinct changes in miRNAs in male and female brain, in addition to a miRNA signature response to ischemia that is common to both.

Impact of gender-age interaction on the outcome of ischemic stroke in an Italian cohort of patients treated according to a standardized clinical pathway

BACKGROUND

Stroke outcome has been reported as worse in women, especially in terms of disability. As for mortality, the data are conflicting, with some reports suggesting a female advantage. Our objective was to explore such issues in an Italian cohort of patients managed by a standardized clinical pathway (CPW) and, as such, homogeneous in terms of clinical management.

METHODS

Data from a cohort of 1993 patients (987 women and 1006 men) with first-ever ischemic stroke, consecutively referred to an in-hospital Clinical Pathway Program from January 1, 2001 to December 31, 2009, were retrospectively analyzed. The relationship between female gender and one-month outcome was assessed with adjustment for age, stroke severity and premorbid disability.

RESULTS

The outcome was worse in women in terms of disability (age-adjusted odds ratio 2.03, 95% CI 1.69-2.46), while no difference was found for mortality. In multivariate models, female gender turned out to be associated with a lower case-fatality rate (adjusted hazard ratio 0.65, 95% CI 0.48-0.89, P=0.007), whereas the odds ratio for disability decreased but remained significant (OR 1.30; 95% CI 1.01-1.69). We found a significant interaction between gender and age in the case-fatality rate, and a female survival advantage was apparent only below 50 years.

CONCLUSIONS

Our study confirms the excess risk of disability after stroke in women, although it is mostly explained by the occurrence of the most severe clinical syndromes. As for mortality, female gender seems to play a protective role, at least in the short-term and in younger patients.

MicroRNA-124 protects neurons against apoptosis in cerebral ischemic stroke

AIMS

To explore the role and underlying mechanism of miR-124 in stroke.

METHODS

miR-124 expression was determined by real-time PCR. The effect of miR-124 on infarct area was assessed in middle cerebral artery occlusion (MCAO) mice. The influence of miR-124 on oxygen and glucose deprivation (OGD) induced neuron apoptosis and death was examined by immunofluorescence. The effect of miR-124 on apoptosis-related proteins was determined by Western blot.

RESULTS

The level of miR-124 is significantly increased in ischemic penumbra as compared with that in nonischemic area of MACO mice. Brain tissue of stroke-prone spontaneously hypertensive rats (SHR-SP) also showed higher level of miR-124 as compared with that of spontaneously hypertensive rats (SHR). Consistently, OGD treatment obviously increased miR-124 level in primary neurons. In vivo, miR-124 overexpression significantly decreased, while miR-124 knockdown significantly increased, the infarct area of MCAO mice. In vitro, gain or loss of miR-124 function resulted in reduced or increased neuron apoptosis and death induced by OGD, and increased or reduced antiapoptosis protein, Bcl-2 and Bcl-xl, respectively.

CONCLUSIONS

miR-124 plays a neurons-protective role via apoptosis-inhibiting pathway in ischemic stroke.

Explicit consideration of baseline factors to assess recombinant tissue-type plasminogen activator response with respect to race and sex

BACKGROUND AND PURPOSE

Sex and race reportedly influence outcome after recombinant tissue-type plasminogen activator (rtPA). It is, however, unclear whether baseline imbalances (eg, stroke severity) or lack of response to thrombolysis is responsible. We applied balancing methods to test the hypothesis that race and sex influence outcome after rtPA independent of baseline conditions.

METHODS

We mapped group outcomes from the National Institute of Neurological Disorders and Stroke (NINDS) dataset based on race and sex onto a surrogate-control function to assess differences from expected outcomes at their respective National Institutes of Health Stroke Scale and age. Outcomes were also compared for subjects matched individually on key baseline factors using NINDS and 2 recent datasets from southeastern United States.

RESULTS

At similar National Institutes of Health Stroke Scale and age, 90-day good outcomes (modified Rankin Score, 0-2) in NINDS were similarly improved after rtPA for white men and women. There was a strong trend for improvement in black men. Conversely, black women treated with rtPA showed response rates no different from the controls. After baseline matching, there were nonsignificant trends in outcomes except for significantly fewer good outcomes in black versus matched white women (37% versus 63%; P=0.027). Pooling the 3 datasets showed a similar trend for poorer short-term outcome for black women (P=0.054; modified Rankin Score, 0-1).

CONCLUSIONS

Matching for key baseline factors indicated that race and sex influence outcome most strikingly in black women who demonstrated poorest outcomes after rtPA. This finding supports the hypothesis that poor response to rtPA, rather than differences in baseline conditions, contributes to the worse outcome. This finding requires prospective confirmation.

The emerging roles of microRNAs in CNS injuries

The consequences of injuries to the CNS are profound and persistent, resulting in substantial burden to both the individual patient and society. Existing treatments for CNS injuries such as stroke, traumatic brain injury and spinal cord injury have proved inadequate, partly owing to an incomplete understanding of post-injury cellular and molecular changes. MicroRNAs (miRNAs) are RNA molecules composed of 20-24 nucleotides that function to inhibit mRNA translation and have key roles in normal CNS development and function, as well as in disease. However, a role for miRNAs as effectors of CNS injury has recently emerged. Use of bioinformatics to assess the mRNA targets of miRNAs enables high-order analysis of interconnected networks, and can reveal affected pathways that may not be identifiable with the use of traditional techniques such as gene knock-in or knockout approaches, or mRNA microarrays. In this Review, we discuss the findings of miRNA microarray studies of spinal cord injury, traumatic brain injury and stroke, as well as the use of gene ontological algorithms to discern global patterns of molecular and cellular changes following such injuries. Furthermore, we examine the current state of miRNA-based therapies and their potential to improve functional outcomes in patients with CNS injuries.

Sex, stroke, and inflammation: the potential for estrogen-mediated immunoprotection in stroke

Stroke is the third leading cause of death and the primary cause of disability in the developed world. Experimental and clinical data indicate that stroke is a sexually dimorphic disease, with males demonstrating an enhanced intrinsic sensitivity to ischemic damage throughout most of their lifespan. The neuroprotective role of estrogen in the female brain is well established, however, estrogen exposure can also be deleterious, especially in older women. The mechanisms for this remain unclear. Our current understanding is based on studies examining estrogen as it relates to neuronal injury, yet cerebral ischemia also induces a robust sterile inflammatory response involving local and systemic immune cells. Despite the potent anti-inflammatory effects of estrogen, few studies have investigated the contribution of estrogen to sex differences in the inflammatory response to stroke. This review examines the potential role for estrogen-mediated immunoprotection in ischemic injury.

The effects of estrogen in ischemic stroke

Stroke is a leading cause of death and the most common cause of long-term disability in the USA. Women have a lower incidence of stroke compared with men throughout most of the lifespan which has been ascribed to protective effects of gonadal steroids, most notably estrogen. Due to the lower stroke incidence observed in pre-menopausal women and robust preclinical evidence of neuroprotective and anti-inflammatory properties of estrogen, researchers have focused on the potential benefits of hormones to reduce ischemic brain injury. However, as women age, they are disproportionately affected by stroke, coincident with the loss of estrogen with menopause. The risk of stroke in elderly women exceeds that of men and it is clear that in some settings estrogen can have pro-inflammatory effects. This review will focus on estrogen and inflammation and its interaction with aging.

Sex differences in stroke

Sex differences in stroke are observed across epidemiologic studies, pathophysiology, treatments, and outcomes. These sex differences have profound implications for effective prevention and treatment and are the focus of this review. Epidemiologic studies reveal a clear age-by-sex interaction in stroke prevalence, incidence, and mortality. While premenopausal women experience fewer strokes than men of comparable age, stroke rates increase among postmenopausal women compared with age-matched men. This postmenopausal phenomenon, in combination with living longer, are reasons for women being older at stroke onset and suffering more severe strokes. Thus, a primary focus of stroke prevention has been based on sex steroid hormone-dependent mechanisms. Sex hormones affect different (patho)physiologic functions of the cerebral circulation. Clarifying the impact of sex hormones on cerebral vasculature using suitable animal models is essential to elucidate male-female differences in stroke pathophysiology and development of sex-specific treatments. Much remains to be learned about sex differences in stroke as anatomic and genetic factors may also contribute, revealing its multifactorial nature. In addition, the aftermath of stroke appears to be more adverse in women than in men, again based on older age at stroke onset, longer prehospital delays, and potentially, differences in treatment.

Post-ischemic estradiol treatment reduced glial response and triggers distinct cortical and hippocampal signaling in a rat model of cerebral ischemia

BACKGROUND

Estradiol has been shown to exert neuroprotective effects in several neurodegenerative conditions, including cerebral ischemia. The presence of this hormone prior to ischemia attenuates the damage associated with such events in a rodent model (middle cerebral artery occlusion (MCAO)), although its therapeutic value when administered post-ischemia has not been assessed. Hence, we evaluated the effects of estradiol treatment after permanent MCAO (pMCAO) was induced in rats, studying the PI3K/AKT/GSK3/β-catenin survival pathway and the activation of SAPK-JNK in two brain areas differently affected by pMCAO: the cortex and hippocampus. In addition, we analyzed the effect of estradiol on the glial response to injury.

METHODS

Male rats were subjected to pMCAO and estradiol (0.04 mg/kg) was administered 6, 24, and 48 h after surgery. The animals were sacrificed 6 h after the last treatment, and brain damage was evaluated by immunohistochemical quantification of 'reactive gliosis' using antibodies against GFAP and Iba1. In addition, Akt, phospho-Akt(Ser473), phospho-Akt(Thr308), GSK3, phospho-GSK3(Ser21/9), β-catenin, SAPK-JNK, and pSAPK-JNK(Thr183/Tyr185) levels were determined in western blots of the ipsilateral cerebral cortex and hippocampus, and regional differences in neuronal phospho-Akt expression were determined by immunohistochemistry.

RESULTS

The increases in the percentage of GFAP- (5.25-fold) and Iba1- (1.8-fold) labeled cells in the cortex and hippocampus indicate that pMCAO induced 'reactive gliosis'. This effect was prevented by post-ischemic estradiol treatment; diminished the number of these cells to those comparable with control animals. pMCAO down-regulated the PI3K/AkT/GSK3/β-catenin survival pathway to different extents in the cortex and hippocampus, the activity of which was restored by estradiol treatment more efficiently in the cerebral cortex (the most affected region) than in the hippocampus. No changes in the phosphorylation of SAPK-JNK were observed 54 h after inducing pMCAO, whereas pMCAO did significantly decrease the phospho-Akt(Ser473) in neurons, an effect that was reversed by estradiol.

CONCLUSION

The present study demonstrates that post-pMCAO estradiol treatment attenuates ischemic injury in both neurons and glia, events in which the PI3K/AKT/GSK3/β-catenin pathway is at least partly involved. These findings indicate that estradiol is a potentially useful treatment to enhance recovery after human ischemic stroke.

Gender and the functional outcome of elderly ischemic stroke patients

The purpose of this study was to investigate the effect of gender on the functional outcome after ischemic stroke. In a retrospective chart review we studied 919 survivors of ischemic stroke admitted for rehabilitation at a geriatric rehabilitation ward of a university affiliated hospital. Functional outcome of female and male patients was assessed by Functional Independence Measurement (FIM) at admission and discharge. Data were analyzed by t test, Chi-square test and Linear Regression. A total number of 919 patients were admitted of whom 56% were males. A higher proportion of male patients reported ischemic heart disease (p<0.001), hypercholesterolemia (p=0.035), Parkinson's disease (p=0.044), and previous stroke (p<0.001). Males had also higher Mini-Mental State Examination (MMSE) scores (p<0.001). Total FIM at admission (62.54 ± 25.98 and 66.00 ± 25.49; p=0.043), and total FIM at discharge (80.39 ± 30.35 and 85.59 ± 29.08; p=0.008), motor FIM at admission (40.04 ± 18.89 and 42.51 ± 18.47; p=0.047) and motor FIM at discharge (56.41 ± 23.04 and 60.44 ± 21.84; p=0.007) were higher among male patients. However, a trend for a borderline statistical difference was observed for FIM gains upon discharge between men and women. A multiple linear regression analysis showed that total FIM at discharge was neither associated with male nor female gender (β=-0.009; p=0.69). The findings suggest that the functional outcome of male survivors presenting for rehabilitation after acute ischemic stroke is slightly better. After adjusting for possible covariates, gender did not emerge as an independent predictor for higher FIM at discharge, suggesting that gender should not be held as adversely affecting rehabilitation of such patients.

X chromosome dosage and the response to cerebral ischemia

Gonadal hormones contribute to ischemic neuroprotection, but cannot fully explain the observed sexual dimorphism in stroke outcomes seen during life stages with low sex steroid hormones. Sex chromosomal complement (XX in females; XY in males) may also contribute to ischemic sexual dimorphism. A transient middle cerebral artery occlusion model was used to investigate the role of X chromosome dosage in female XX and XO littermates of two mouse strains (Paf and Eda(Ta)). Cohorts of XX and XO gonadally intact, ovariectomized, and ovariectomized females supplemented with estrogen were examined. Infarct sizes were equivalent between ovariectomized XX and XO mice, between intact XX and XO mice, and between estrogen-supplemented ovariectomized XX and XO mice. This is the first study to investigate the role of sex chromosome dosage in the response to cerebral ischemia. Neither the number of X chromosomes nor the parent of origin of the remaining X chromosome had a significant effect on the degree of cerebral infarction after experimental stroke in adult female mice. Estrogen was protective against cerebral ischemia in both XX and XO mice.

Reproductive age modulates the impact of focal ischemia on the forebrain as well as the effects of estrogen treatment in female rats

While human observational studies and animal studies report a neuroprotective role for estrogen therapy in stroke, the multicenter placebo-controlled Women's Health Initiative (WHI) study concluded that hormone therapy increased the risk for stroke in postmenopausal women. The present study therefore tested the hypothesis that estrogen replacement would increase the severity of a stroke-like injury in females when this replacement occurs after a prolonged hypoestrogenic period, such as the menopause or reproductive senescence, but not when given to females that were normally cycling immediately prior to the hormone replacement. Two groups of female rats were used: multiparous females with normal but lengthened estrus cycles (mature adults), and older multiparous females currently in a persistent acyclic state (reproductive senescent). Animals were either used intact, or were bilaterally ovariectomized and immediately replaced with a 17beta-estradiol pellet or control pellet. Animals were subject to a forelimb placing test (a test for sensorimotor deficit) and thereafter to middle cerebral artery occlusion (MCAo) by stereotaxic injection of the vasoconstrictive peptide endothelin-1, adjacent to the MCA. One week after stroke, behavioral tests were performed again. Cortical and striatal infarct volume, measured from brain slices, was significantly greater in intact reproductive senescent females as compared to intact mature adults. Furthermore, estrogen treatment to ovariectomized mature adult females significantly reduced the cortical infarct volume. Paradoxically, estrogen treatment to ovariectomized reproductive senescent females significantly increased cortical and striatal infarct volumes as compared to control pellet replaced senescent females. Significant post-stroke behavioral deficit was observed in all groups on the side contralateral to the lesion, while senescent females also exhibited deficits on the ipsilateral side, in the cross-midline forelimb placement test. Using an animal model that approximates the natural ovarian aging process, these findings strongly support the hypothesis that the effectiveness of estrogen therapy in protecting brain health may depend critically on the time of initiation with respect to a female's reproductive status.